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ISO7841: Safety Certification Specs of the ISO784xF & Working Voltage

Part Number: ISO7841

Hello E2E,

My questions pertain to the safety certification specifications of the ISO784xF from sections 6.6 and 6.7 of the datasheet. Our product is intended for sale in the US, EU, and Asia and we are designing our product under the guidelines of IEC 61010-1. The DWW package of the isolator being rated as material group I is helpful along with the general specification for Viowm of 2828VDC per VDE 0884-10, but…

  • UL certified to 5700Vrms with a “single isolation” caveat
  • It looks like the 5700Vrms is a type test for withstand voltage per UL 1577?
  • Where does the “single isolation” caveat come from?
  • What is the max DC reinforced working voltage for the ISO784xF per UL?
  • TuV shows 1000Vrms reinforced (per 61010-1) yet 1450Vrms (per 60950)
  • Where does the 61010 limit of 1000V come from? Is this a construction spacing constraint?
  • What is the max DC reinforced working voltage for the ISO784xF per TUV?

  • Hi Timothy,

    1) Yes, 5700 Vrms is a type test for withstand voltage per UL 1577.

    2) All our digital isolators are certified for 'Single Protection' according to UL 1577. For 'Double Protection', isolators have to pass a peculiar 20 kV discharge test that our isolators have not been evaluated against. That said, we have reinforced insulation rating from VDE, CSA, CQC, and TUV. TUV reinforced rating also covers UL 61010-1 certification. You can find out more about UL single and double protection from my post at:

    3) UL 1577 doesn't have a working voltage requirement; it only specifies isolation withstand voltage (5700 Vrms). For other standards, all our working voltage certifications were done for AC (RMS or PK) voltages because they are more stressful for the isolation barrier than DC voltage. We have done internal evaluation of DC voltage performance and the device can easily withstand 2828V DC for it's lifetime. For UL 61010-1, the standard limits the working voltage to 1000 V.

    4) IEC 61010-1 and IEC 60950-1 has different in how they constraint the working voltage and other requirements. For detailed system-level constraints, you should check with your certification agency.

    5) As mentioned earlier, all our working voltages were certified for AC but the device can easily sustain the same level of DC voltage. For specific standard-related constraints, you need to check with your certification agency.

  • Hi Saleem,

     

    Thank you for your responses – I’d like to dig a bit deeper on this product:

    1. Regarding IEC 61010-1:
      • Why is IEC 61010-1 included as a certification for the ISO7841?
        • I ask because my understanding is that IEC 61010-1 pertains to end systems implemented as electrical measurement and source equipment (as often found in a laboratory), or equipment capable of controlling other devices. Because the ISO7841 is a single component, not yet implemented, I’m seeking clarification on why this system-level standard is included.
      • Where does the 1000V limit derive from in answer #3?
        • IEC 61010-1 covers much more than 1000VDC, even for secondary circuits, as seen in Table K.13 (up to 63 kV covered).

    2. Regarding DWW package construction:

      • For the TUV/EN 61010-1 spec of 1000 Vrms reinforced working voltage, for the DWW package, would you be able to clarify which part of the standard was referenced for certification? For example, Table K.5, or Section K.1.3.2?

     

    Thank you for any insights,

    Tim

  • Hi Tim,

    Following are the responses:

    1. Regarding IEC61010-1:

    • You are correct, IEC 61010-1 is a system-level standard and typically end-equipment is certified to this standard. Isolation components, like ISO7841, are only certified to specific insulation-related clauses of the standard and not the whole standard. It then becomes easier for end-equipment manufacturers to certify their product if they use a component that's already certified for insulation clauses.
    • According to table K.13: For 1000 Vrms/Vdc working voltage, you need at least 5mm Creepage (for basic insulation, material group I, pollution degree 2) and 10 mm Creepage (for reinforced insulation). So working voltages are limited by our device's Creepage. Also, Clearances can limit the working voltage based on whether your end application will be in Overvoltage Category II, III, or IV (see tables K.11, K.12, K.13).

    2. Regarding DWW package construction:

    • ISO7841 complies with 1000 Vrms reinforced working voltage per table K.5.